Method for manufacturing a rotor for synchronous motor

ABSTRACT

A rotor (10) includes a plurality of permanent magnets (14) disposed around a shaft (12) at generally equal intervals, and a plurality of laminated core members (16) disposed between the permanent magnets (14) so as to form magnetic poles. The laminated core members (16) are formed by stacking a plurality of core-laminations (26) made of magnetic materials and an integral core-lamination, and joining them to each other. The integral core-lamination includes a plurality of core-lamination sections each having a shape the same as that of the core-lamination (26), and connecting portions (46) for connecting adjacent core-lamination sections with each other. When the large number of core-laminations (26) and the integral core-lamination are integrally joined by a press-fitting process, the laminated core members (16) are connected with each other in such a relative arrangement of a finished assembly that a space for locating the permanent magnet (14) is defined between the adjacent laminated core members (16), and thus an integral laminated rotor core (48) is formed.

This is a division of application Ser. No. 08/318,676 filed Oct. 14,1994, now abandoned.

TECHNICAL FIELD

The present invention relates to a rotor for a synchronous motor, whichincludes a plurality of permanent magnets disposed around a shaft andmagnetized alternately in a circumferential direction, and a pluralityof laminated core members disposed around the shaft while holding eachpermanent magnet therebetween in the circumferential direction so as toform magnetic poles.

BACKGROUND ART

In the field of synchronous motors, a rotor as mentioned above, whichincludes permanent magnets magnetized in a circumferential direction andlaminated core members each forming a magnetic pole between thepermanent magnets, the magnets and the core members being alternatelydisposed around a shaft, has been used. In this type of conventionalrotor, each laminated core member is generally formed by stacking aplurality of core-laminations made of magnetic materials such as siliconsteel plates. Each core-lamination may have recesses and projections,which are formed at corresponding positions on respective axial endfaces of core-lamination and can be engaged with each other. Thecore-laminations can be joined to each other by, e.g., press-fitting thecore-laminations together while aligning the recesses and projections ofthe adjacent core-laminations. Each permanent magnet is held between apair of adjacent laminated core members and brought into close contactwith the side faces of the latter. The permanent magnet may bepositioned and fixedly supported in a radial direction by outer andinner hooks protruding from the side faces of each laminated core memberat outer and inner peripheral regions thereof. A rod member may beinserted into an axial through hole formed generally at the center ofeach laminated core member. Each rod member may be connected to annularend plates which are arranged at both axial ends of the laminated coremember and fixed to the rotating shaft. In this manner, the laminatedcore members and the permanent magnets are fixedly held in the rotoragainst external force such as centrifugal force, by the end plates, therod members and the hooks.

This type of rotor uses a plurality of permanent magnets and laminatedcore members, the number of which corresponds to the number of magneticpoles, therefore it has problems in that the work of positioning orfixing the permanent magnets and laminated core members is complicated,increased working time and skilled workers are required, and thusimprovement of personnel requirements and productivity is prevented.Further, the accuracy of positioning the permanent magnets and laminatedcore members depends on the mechanical strength and processing accuracyof the rod members and end plates. Consequently, in the case of highspeed motors or high torque motors, additional means for improving themechanical strength of the whole structure of the rotor is required inorder to accurately hold the permanent magnets and laminated coremembers in predetermined positions.

DISCLOSURE OF THE INVENTION

An object of the preset invention is to provide a method formanufacturing a rotor for a synchronous motor including permanentmagnets and laminated core members disposed around a rotating shaftalternately in a circumferential direction, which can facilitatepositioning or fixing processes of the permanent magnets and laminatedcore members in an assembling process so as to improve productivity, andalso can improve mechanical strength and thus performance andreliability of a high speed or high torque motor.

To accomplish the above objects, the present invention provides a rotorfor a synchronous motor comprising a shaft; a plurality of permanentmagnets disposed around the shaft at generally equal intervals; aplurality of core members disposed around the shaft while holding eachof the permanent magnets therebetween in a circumferential direction, soas to form magnetic poles; supporting means for fixedly supporting thepermanent magnets and the core members onto the shaft; and connectingmeans for connecting the core members located at desired positionsaround the shaft with each other in a relative arrangement of a finishedrotor assembly.

In the rotor according to the present invention, the connecting meansenables the core members located at desired positions to be integrallyhandled in a state in which they are already relatively positioned.Accordingly, the productivity for assembling a rotor is significantlyimproved, and, after being assembled, the mechanical strength of a rotorstructure is improved because the connecting means assists the supportof the core members and the permanent magnets against an external forcesuch as a centrifugal force.

In a preferred embodiment of the present invention, each of the coremembers is a laminated core member formed by axially stacking andjoining a plurality of core-laminations made of magnetic materials, andthe connecting means comprises at least one integral core-laminationmade of a magnetic material, the integral core-lamination includingsections which are inserted between the core-laminations of thelaminated core members located at the desired positions and are joinedto adjacent core-laminations. In this case, the integral core-laminationmay include core-lamination sections having shapes generally the same asthose of the core-laminations of the laminated core members and thenumber thereof being the same as the number of magnetic poles so as tobe inserted and joined between the core-laminations, and also includeconnecting portions extended from the core-lamination sections so as toannularly connect all of the core-lamination sections in a predeterminedarrangement, whereby all of the core-lamination sections are connectedin such a relative arrangement of a finished rotor assembly that a spacefor locating each permanent magnet is defined between adjacentcore-lamination sections, so as to form an integral laminated rotorcore. Alternatively, the integral core-lamination may includecore-lamination sections having shapes being generally the same as thoseof the core-laminations of the laminated core members and the numberthereof being half the number of magnetic poles so as to be inserted andjoined between the core-laminations, and connecting portions extendedfrom the core-lamination sections so as to annularly connect all of thecore-lamination sections in a predetermined arrangement, whereby all ofthe laminated core members forming the same magnetic poles are connectedin such a relative arrangement of a finished assembly that a space forlocating one laminated core member forming another magnetic pole and twopermanent magnets is defined between adjacent core-lamination sections.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and the other objects, features, and advantages of thepresent invention will be described with reference to the embodimentsshown in the accompaning drawings, in which;

FIG. 1A is a side view of a rotor according to an embodiment 1 of thepresent invention;

FIG. 1B is a sectional view taken along line I--I of FIG. 1A;

FIG. 2A is a perspective view of an integral laminated rotor core of therotor shown in FIG. 1A;

FIG. 2B is a perspective view of a part taken along line II--II of FIG.2A;

FIG. 3A is a plan view of a core-lamination of the integral laminatedrotor core shown in FIG. 2A;

FIG. 3B is a sectional view taken along line III--III of FIG. 3A;

FIG. 4 is a plan view of an integral core-lamination of the integrallaminated rotor core shown in FIG. 2A;

FIG. 5A is a side view of a rotor according to an embodiment 2 of thepresent invention;

FIG. 5B is a sectional view taken along line V--V of FIG. 5A;

FIG. 6 is a perspective view of an integral laminated rotor core of therotor shown in FIG. 5A;

FIG. 7 is a plan view of a core-lamination of the integral laminatedrotor core shown in FIG. 6;

FIG. 8 is a plan view of an integral core-lamination of the integrallaminated rotor core shown in FIG. 6;

FIG. 9 is a plan view of an integral core-lamination of a rotoraccording to an embodiment 3 of the present invention;

FIG. 10 is a perspective view of an integral laminated rotor core usingthe integral core-lamination shown in FIG. 9;

FIG. 11A is a perspective view of an integral laminated rotor core of arotor according to an embodiment 4 of the present invention;

FIG. 11B is a schematic view of a laminated construction of the integrallaminated rotor core shown in FIG. 11A;

FIG. 12A is a perspective view of an integral laminated rotor core of arotor according to an embodiment 5 of the present invention;

FIG. 12B is a schematic view of a laminated construction of the integrallaminated rotor core shown in FIG. 12A;

FIG. 13 is a plan view of an integral core-lamination of a rotoraccording to an embodiment 6 of the present invention;

FIG. 14 is a sectional view of a rotor according to an embodiment 7 ofthe present invention;

FIG. 15A and 15B are plan views of integral core-laminations of a rotorshown in FIG. 14;

FIG. 16A is a perspective view of two integral laminated rotor cores ofthe rotor shown in FIG. 14;

FIG. 16B is a perspective view of a part taken along line XVI--XVI ofFIG. 16A;

FIG. 17 is a plan view of a modification of a core-lamination of theintegral laminated rotor core shown in FIG. 16;

FIG. 18 is a sectional view of a rotor according to an embodiment 8 ofthe preset invention;

FIGS. 19A and 19B are plan views of integral core-laminations of a rotorshown in FIG. 18;

FIG. 20 is a sectional view of a rotor according to an embodiment 9 ofthe present invention;

FIG. 21 is a flow chart showing a manufacturing process of the integrallaminated rotor core shown in FIG. 11A;

FIG. 22 is an illustration of stamped products formed at respectivesteps according to the manufacturing process shown in FIG. 21; and

FIG. 23 is an illustration showing a manufacturing process of theintegral laminated rotor core shown in FIG. 14 by stamped productsformed at respective steps thereof.

BEST MODE OF CARRYING OUT THE INVENTION

In the following description of embodiments, the same or similarcomponents are represented by the same reference numerals.

Embodiment 1

Referring to the drawings, FIGS. 1A and 1B show a rotor 10 for asynchronous motor according to the embodiment 1 of the presentinvention. The rotor 10 includes a shaft 12, a plurality (six in thisembodiment) of permanent magnets 14 disposed around the shaft 12 atgenerally equal intervals and magnetized alternately in acircumferential direction, and a plurality (six in this embodiment) oflaminated core members 16 disposed around the shaft 12 while holdingeach permanent magnet 14 therebetween in the circumferential directionso as to form magnetic poles. Each permanent magnet 14 is held betweenand brought into close contact with the side faces of adjacent laminatedcore members 16. Each laminated core member 16 includes outer hooks 18protruding from both side faces at outer peripheral regions thereof.Therefore, each permanent magnet 14 is positioned in a radial directionby the outer hook 18 of the laminated core member 16 and fixedlysupported against centrifugal force. The laminated core members 16 arerespectively provided with rod holes 20 axially penetrating through thegenerally center portions of the core members, and rod members 22 areinserted into respective rod holes 20. These rod members 22 areconnected to a pair of annular end plates 24 arranged at both axial endsof the laminated core members 16. Each end plate 24 is fixed to theshaft 12 by shrink fitting or bonding.

As shown in FIGS. 2A and 2B, the laminated core members 16 forming sixmagnetic poles of the rotor 10 are formed by stacking a plurality ofcore-laminations 26 made of magnetic materials such as silicon steelplates and joining them to each other. As more clearly shown in FIGS. 3Aand 3B, the core-lamination 26 has a generally sector shape in a planview, which includes an arcuate inner edge 28 adapted to surround theshaft 12, an outer edge 30 with a predetermined curved-out shape adaptedto be opposed to a stator (not shown), and both sides 32 adapted to bebrought into contact with the permanent magnet 14. The core-lamination26 is provided at both sides 32 thereof with outer hook elements 18'extended from the outer edge 30, and at the center thereof with a rodhole element 20'. When the core-laminations 26 are stacked in an exactlysuperimposed manner, the outer hook elements 18' and the rod holeelements 20' are axially joined and form the outer hook 18 and the rodhole 20. The core-lamination 26 is provided on respective axial endfaces thereof with a recess 34 and a projection 36 formed at acorresponding position, the projection being able to be fitted into therecess. The core-laminations 26 are stacked in such a manner that therecess 34 and the projection 36 of the adjacent core-laminations 26 arealigned with each other, and after that the core-laminations 26 arejoined together by a press-fitting process using, e.g., a press machine(not shown).

As shown in FIGS. 2A and 2B, a plurality of integral core-laminations 38are inserted or arranged at predetermined positions in a laminatedconstruction formed by the core-laminations 26 of each laminated coremember 16. As shown in FIG. 4, the integral core-lamination 38 includessix core-lamination sections 40 each having the same shape as thecore-lamination 26. Each core-lamination section 40 is stacked andjoined together with the large number of core-laminations 26 in theabove-mentioned manner to form the laminated core member 16. Thecore-lamination section 40 includes connecting portions 46 extended inthe circumferential direction from both sides 42 at an inner edge 44 ofthe core-lamination section. The core-lamination sections 40 aremutually connected through the connecting portions 46 in such a relativearrangement that a space for locating the permanent magnet 14 is definedbetween the adjacent core-lamination sections 40. In this manner, theintegral core-lamination 38, of which all core-lamination sections 40are annularly connected, is formed.

In the illustrated embodiment, four integral core-laminations 38 arearranged at two positions dividing the laminated length of thecore-laminations 26 of each laminated core member 16 into threegenerally equal parts; two integral core-laminations being arranged ateach of the two positions. When the large number of core-laminations 26and the four integral core-laminations 38, which are arranged in thismanner, are joined together by a press-fitting process, the laminatedcore members 16 are mutually connected in such a relative arrangement ofa finished assembly that a space for locating the permanent magnet 14 isdefined between the adjacent laminated core members 16 as shown in FIG.1B, whereby an integral laminated rotor core 48 is formed (see FIG. 2A).It should be noted that a different number of the integralcore-laminations 38 may be provided other than the above-mentionednumber, but preferably a small number are provided as long as themechanical strength of the connecting structure between the laminatedcore members can be maintained, from the viewpoint of the reduction ofmagnetic leakage. Also, the integral core-laminations 38 may havevarious arrangements in the laminated structure other than theabove-mentioned arrangement, but preferably have a regular andsymmetrical arrangement in order to obtain an entirely balancedstrength.

The connecting portions 46 of the integral core-lamination 38 are formedrelatively thin as long as the mechanical strength can be maintained, inorder to prevent magnetic leakage as much as possible. As shown in FIG.1B, in the integral laminated rotor core 48, the connecting portions 46of the integral core-lamination 38 are abutted onto the inner surfacesof the permanent magnets 14, which are opposed to the shaft 12, andcooperate with the outer hooks 18 of the laminated core members 16 so asto position and fixedly support the permanent magnets 14. Consequently,the laminated core members 16 do not require inner hooks as used in aconventional structure, and the magnetic leakage caused by the innerhooks can be eliminated. Thus, it has been observed that the magneticleakage in the integral laminated rotor core 48 is, as a whole, aboutthe same as that in the conventional structure.

The integral laminated rotor core 48 having the above-mentionedstructure makes it possible to integrally handle the laminated coremembers 16 with the same number (six in this embodiment) as the numberof magnetic poles in a state in which they are previously positionedrelative to each other. Accordingly, in the assembling process of therotor 10, the permanent magnets 14 can be held between the laminatedcore members 16 merely by inserting and fitting the permanent magnets 14into the spaces for locating permanent magnets defined in the integrallaminated rotor core 48, whereby the productivity is remarkably improvedin the subsequent step of fitting to the shaft 12.

Embodiment 2

FIGS. 5A and 5B show a rotor 50 according to an embodiment 2 of thepresent invention. The rotor 50 includes an integral laminated rotorcore 52 which has a structure similar to the integral laminated rotorcore 48 of the embodiment 1. As shown in FIG. 6, the integral laminatedrotor core 52 includes a plurality of laminated core members 56 whichare formed by stacking and joining the large number of core-laminations54. These laminated core members 56 are connected together by integralcore-laminations 58 which are inserted into the predetermined positionsin the laminated structure of the core-laminations 54 and joinedtogether with the latter. As shown in FIG. 7, the core-lamination 54 hassubstantially the same shape as the core-lamination 26 of the embodiment1, except that inner hooks 64' are extended in a circumferentialdirection from both sides 60 at an inner edge 62. The inner hooks 64'form inner hooks 64 of the laminated core member 56 by stacking aplurality of core-laminations 54. The inner hooks 64 cooperate withouter hooks 66 so as to position and fixedly support the permanentmagnet 14.

As shown in FIG. 6, two integral core-laminations 58 are arranged at twopositions dividing the laminated length of each laminated core member 56into three generally equal parts, in the same manner as theembodiment 1. Of course, other numbers or arrangements of the integralcore-laminations 58 may be adopted. As shown in FIG. 8, the integralcore-lamination 58 includes a plurality of core-lamination sections 68each having the same shape as the core-lamination 54. Eachcore-lamination section 68 is stacked and joined together with the largenumber of core-laminations 54 so as to form the laminated core member56. The core-lamination section 68 includes connecting portions 74extended in the circumferential direction from both sides 70 at an outeredge 72 of the core-lamination section. The core-lamination sections 68are mutually connected through the connecting portions 74 in such arelative arrangement that a space for locating the permanent magnet 14is defined between the adjacent core-lamination sections 68.

In the rotor 50 including the integral core-laminations 58, theconnecting portions 74 for forming the integral laminated rotor core 52are provided on the outer peripheral edge region adapted to be opposedto a stator, therefore the magnetic leakage performance and theinfluence for magnetic flux distribution in an air-gap between thestator and rotor are inferior to some extent to the embodiment 1.However, the connecting portions 74 reinforce the support of thepermanent magnets against an external force such as a centrifugal force,and thereby improve the mechanical strength of the rotor structure.

Embodiment 3

The rotor according to the present invention may use an integralcore-lamination 76 as shown in FIG. 9, in order to form an integrallaminated rotor core. The integral core-lamination 76 includes aplurality of core-lamination sections 78 which have substantially thesame shape as the core-lamination 26 of the embodiment 1. Eachcore-lamination section 78 includes outer peripheral connecting portions84 extended in the circumferential direction from both sides 80 at anouter edge 82 and inner peripheral connecting portions 88 extended inthe circumferential direction from both sides 80 at an inner edge 86.The core-lamination sections 78 are mutually connected through the outerand inner peripheral connecting portions 84 and 88 in such a relativearrangement that a space 90 for locating a permanent magnet is definedbetween the adjacent core-lamination sections 78.

Each core-lamination section 78 of the integral core-lamination 76 isstacked and joined with the core-laminations 26 of the embodiment 1. Anintegral laminated rotor core 94 as shown in FIG. 10 is formed in thismanner, which includes a plurality of laminated core members 92connected to each other. In the case of using the integralcore-lamination 76, the magnetic leakage performance and the influenceon magnetic flux distribution in an air-gap are inferior to some extentto the embodiment 1, because the structure has the outer peripheralconnecting portions 84. However, the mechanical strength of the integrallaminated rotor core 94 is more stable than that of both the aboveembodiments. Also, the productivity for assembling the rotor is betterthan both of the above embodiments.

Embodiment 4

An integral laminated rotor core 96 as shown in FIG. 11A is formed byreplacing two of four integral core-laminations 38 of the innerperiphery connecting type (FIG. 4), in the integral laminated rotor core48 of the embodiment 1, with the integral core-laminations 76 of theinner and outer peripheries connecting type (FIG. 9). From the viewpointof rotor balance, it is preferred that one integral core-lamination 38is directly superimposed on one integral core-lamination 76 as shown inFIG. 11B and they are arranged at two positions that divide thelaminated length of rotor into three generally equal parts. The integrallaminated rotor core 96 has a mechanical strength greater than that ofthe integral laminated rotor core 48 of the embodiment 1 and a magneticperformance superior to that of the integral laminated rotor core 94 ofthe embodiment 3.

Embodiment 5

An integral laminated rotor core 98 as shown in FIG. 12A is formed byadding two integral core-laminations 58 of the outer peripheryconnecting type (FIG. 8) to the integral laminated rotor core 48 of theembodiment 1, which includes four integral core-laminations 38 of theinner periphery connecting type (FIG. 4). In the illustrated embodiment,from the viewpoint of rotor balance, two mutually superimposed integralcore-laminations 58 are arranged at a generally center position betweenthe positions of the two integral core-laminations 38 as shown in FIG.2B (see FIG. 12B). The integral laminated rotor core 98 has a mechanicalstrength and a magnetic performance generally equal to those of theintegral laminated rotor core 96 of the embodiment 4.

Embodiment 6

FIG. 13 shows an integral core-lamination 100 with a different shape,used to form an integral laminated rotor core according to the presentinvention. The integral core-lamination 100 includes a plurality ofcore-lamination sections 102, each of which has the same shape as thecore-lamination 54 of the embodiment 2 (FIG. 7). Each core-laminationsection 102 is inserted into the predetermined position in the laminatedstructure of the large number of core-laminations 54 and joined togetherwith the latter. Each core-lamination section 102 includes a firstconnecting portion 106 extended in a radially inward direction fromgenerally the center of an inner edge 104 of the core-laminationsection, and is supported by an annular connecting portion 108 adaptedto surround the shaft 12 through the first connecting portion 106. Inthis manner, the core-lamination sections 102 are mutually connected insuch a relative arrangement that a space for locating a permanent magnet14 is defined between the adjacent core-lamination sections 102.

In the case of using the integral core-laminations 100 of the embodiment6 in place of the integral core-laminations 58 in the integral laminatedrotor core 52 of the embodiment 2, the magnetic leakage through thefirst connecting portions 106 and the annular connecting portion 108 isextremely reduced, because the first connecting portions 106 aredisposed at the region having low magnetic flux density from theviewpoint of magnetic flux flow (shown as arrows in FIG. 13) when thepermanent magnets 14 are assembled in the integral laminated rotor core52. The effect of this embodiment on preventing magnetic leakage isextremely superior in comparison with the effect of the embodiment 1. Itis noted that a plurality of first connecting portions 106 may beextended in parallel from the general center region of the inner edge104 of the core-lamination section 102 to such an extent that themagnetic leakage is not increased. In this case, the stiffness of thelaminated core member 56 (FIG. 6) against revolution about the firstconnecting portion 106 is increased.

Embodiment 7

In the above-mentioned embodiments, there is a problem as to how themagnetic leakage can be inhibited, which is caused by the connectingportions of the integral core-lamination used for forming the integrallaminated rotor core. In this respect, by integrating only the laminatedcore members of the same pole instead of integrating all laminated coremembers of the rotor, the magnetic leakage can be substantiallyeliminated.

A rotor 110 as shown in FIG. 14 includes a plurality of laminated coremembers 112, 114, both being formed by stacking the large number ofcore-laminations 54, in the same manner as the embodiment 2. Thelaminated core members 112 and 114 are alternately magnetized by thepermanent magnets 14. In the illustrated embodiment, three laminatedcore members 112 establishing N-poles are mutually connected throughfirst integral core-laminations 116 which are inserted and joined to thepredetermined positions in a laminated structure, and three laminatedcore members 114 establishing S-poles are mutually connected throughsecond integral core-laminations 118 which are inserted and joined tothe predetermined positions in a laminated structure.

As shown in FIGS. 15A and 15B, the first integral core-lamination 116has the same structure as the second integral core-lamination 118, andboth include three core-lamination sections 120 each having the sameshape as the core-lamination 54. Each core-lamination section 120includes a first connecting portion 124 extended in a radially inwarddirection from a generally center of an inner edge 122 of thecore-lamination section, and is supported by an annular connectingportion 126 adapted to surround the shaft 12 (FIG. 14) through the firstconnecting portion 124. In this manner, the core-lamination sections 120are mutually connected in such a relative arrangement that a space forlocating two permanent magnets 14 (FIG. 14) and one another pole'score-lamination section 120 is defined between the adjacentcore-lamination sections 120.

As shown in FIGS. 16A and 16B, four first integral core-laminations 116are mutually superimposed and arranged at a position spaced a distanceof generally one-third of a laminated length from one axial end face ofthe laminated core member 112 establishing a N-pole, and thecore-lamination sections 120 thereof are joined together with the largenumber of core-laminations 54 by a press-fitting process. Also, foursecond integral core-laminations 118 are mutually superimposed andarranged at a position spaced a distance of generally one-third of alaminated length from one axial end face of the laminated core member114 establishing a S-pole, and the core-lamination sections 120 thereofare joined together with the large number of core-laminations 54 by apress-fitting process. In this manner, an integral laminated rotor core128 for N-poles and an integral laminated rotor core 130 for S-poles areformed. Then, the integral laminated rotor core 128 for N-poles and theintegral laminated rotor core 130 for S-poles are assembled together insuch a manner that the respective three laminated core members 112 and114 are positioned alternately in a circumferential direction, and thatthe annular connecting portions 126 of the respective integralcore-laminations 116 and 118 do not interfere with each other. Afterthat, the permanent magnets 14 are inserted between the respectiveadjacent laminated core members 112, 114. In this state, the integrallaminated rotor cores 128 and 130 are fixedly installed onto the shaft12 through the rod members 22 and the end plates 24 in the same manneras the embodiments 1 to 6, whereby the rotor 110 shown in FIG. 14 isformed.

In the rotor 110, the laminated core members 112, 114 of the samemagnetic poles are respectively integrated, therefore, in comparisonwith the structures of the embodiments 1 to 6, in which all laminatedcore members are integrated, the assembling productivity is inferior tosome extent but the magnetic leakage is substantially eliminated. Ofcourse, it has a superior workability in comparison with theconventional structure in which all laminated core members areseparated. The integral core-laminations 116, 118 may have variousarrangements and different numbers of the laminated core members 112,114, other than those mentioned above. However, it is necessary toeliminate a mutual contact between the annular connecting portions 126of the integral core-laminations 116, 118 when the integral laminatedrotor core 128 for N-poles is assembled with the integral laminatedrotor core 130 for S-poles. Further, a well balanced arrangement as awhole is required.

The connecting construction between the core-lamination sections 120 ofthe integral core lamination 116, 118 is not restricted as the first andannular connecting portions 124 and 126 as mentioned above, but may useconnecting portions 132 each having a shape easily made by a stampingprocess, as shown in FIG. 17. In the case of using this shape, theconnecting portions 132 must be formed so as to eliminate any contactwith the adjacent core-laminations 54 of another pole.

Embodiment 8

A rotor 134 shown in FIG. 18 includes a shaft 136 made of a non-magneticmaterial such as a stainless steel. Further, a first integralcore-lamination 138 shown in FIG. 19A is used to connect the laminatedcore members 112 for N-poles with each other, and a second integralcore-lamination 140 shown in FIG. 19B is used to connect the laminatedcore members 114 for S-poles with each other. Each of the integralcore-laminations 138, 140 has a structure similar to that of eachintegral core-lamination 116, 118 in the embodiment 7, but, regardingthe connecting construction between the core-lamination sections,includes a plurality of first connecting portions 142 and an annularconnecting portion 144 both having higher strength. The inner diameterof the annular connecting portion 144 is generally equal to the outerdiameter of the shaft 136. Therefore, the annular connecting portion 144is closely fit to the shaft 136, whereby the mechanical strength of therotor 134, particularly the strength against radial load applied to theshaft 136, can be further improved.

Embodiment 9

In the rotor of the embodiments 1 to 8, it is possible to form ahigh-power multi-section rotor by disposing axially side by side aplurality of integral laminated rotor cores with the same structure. Forexample, as shown in FIG. 20, two integral laminated rotor cores 48 inthe embodiment 1 are disposed axially side by side through a circularplate member 146, and are fixedly installed to the shaft 12 through therod members 22 and the end plates 24, whereby a high-power rotor 148 canbe formed. In this case, the permanent magnets 14 of the embodiment 1may be used as they are, or longer permanent magnets having overalllengths corresponding to the total length of two integral laminatedrotor cores 48 may be used.

Manufacturing Process

The integral laminated rotor cores of the rotors according to theembodiments 1 to 9 can be conveniently manufactured by one progressivedie machine which can carry out various processes while choosing desiredpress-stations, from the viewpoint of maintaining productivity. Amanufacturing process for an integral laminated rotor core 96 accordingto the embodiment 4 is schematically described, by way of example, withreference to FIGS. 21 and 22. In this case, an integral core-lamination76 of inner and outer peripheries connecting type (FIG. 9) is formed asa basic shape by stamping a flat rolled magnetic steel sheet, at a firststation S1. The integral core-lamination 76 is conveyed successively tofollowing stations by a conveying device of the progressive die machine.At a next station S2, whether to cut outer peripheral connectingportions 84 or not is decided. If the integral core-lamination was notcut at the outer portions 84, it is conveyed to the last station S4 soas to be used as the integral core-lamination 76. Further at a nextstation S3, whether to cut inner peripheral connecting portions 88 ornot is decided. If the integral core-lamination was not cut at the innerportions 88, it is conveyed to the last station S4 so as to be used asan integral core-lamination 38 of inner periphery connecting type (FIG.4), and if the integral core-lamination was cut at the inner portions88, it is conveyed to the last station S4 so as to be used as sixcore-laminations 26 while keeping the relative arrangement. At the laststation S4, the integral core-laminations 76, the integralcore-laminations 38 and the core-laminations 26 are collected into theabove-mentioned stacking arrangement, and are joined with each other bypress-fitting, so as to form the integral laminated rotor core 96.

FIG. 23 shows a manufacturing process for an integral laminated rotorcore 128 for N-poles and an integral laminated rotor core 130 forS-poles according to the embodiment 7, which uses the above progressivedie machine. First, an integral core-lamination (identical to theintegral core-lamination 100 in the embodiment 6), of which allcore-lamination sections 120 are connected by an annular connectingportion 126, is formed as a basic shape by stamping a flat rolledmagnetic steel sheet, at a first station S1. At a next station S2,whether to cut every other one of first connecting portions 124 of thecore-lamination sections 120 or not is decided. If the integralcore-lamination was not cut, it is conveyed to a next station S3.Further at the next station S3, whether to cut first connecting portions124 of the remaining three core-lamination sections 120 or not isdecided. If the integral core-lamination was not cut at the stations S2and S3, it is conveyed to the last station S4, after removing theannular connecting portion 126, so as to be used as six separatedcore-laminations 54 while keeping the relative arrangement. If theintegral core-lamination was cut at the station S2 and was not cut atthe station S3, it is conveyed to the last station S4 so as to be usedas a first integral core-lamination 116 and three separatedcore-laminations 54 while keeping the relative arrangement. If theintegral core-lamination was not cut at the station S2 and was cut atthe station S3, it is conveyed to the last station S4 so as to be usedas a second integral core-lamination 118 and three separatedcore-laminations 54 while keeping the relative arrangement. At the laststation S4, the first integral core-laminations 116, the second integralcore-laminations 118 and the core-laminations 54 are collected into theabove-mentioned stacking arrangement, and are joined with each other bypress-fitting, so as to respectively form the integral laminated rotorcore 128 for N-poles and the integral laminated rotor core 130 forS-poles in a relative arrangement of a finished assembly.

As is clear from the above description, the present invention providesan integral laminated rotor core in which laminated core members formingmagnetic poles are connected with each other, by inserting at least oneintegral core-lamination into the laminated structure of the laminatedcore members. Therefore, the work of positioning or fixing permanentmagnets and laminated core members in an assembling process of a rotoris facilitated, and productivity is significantly improved. Further, themechanical strength of a rotor is improved by the integral laminatedrotor core. Consequently, the performance and reliability of high speedor high torque motors can be improved by using the rotor according tothe present invention.

The present invention has been described in relation to the variousembodiments shown in the attached drawings, but is not restricted by theabove descriptions, and various changes and modifications can be carriedout without departing from the spirit and scope of the invention recitedin the appended claims.

We claim:
 1. A method of manufacturing a rotor for a synchronous motorcomprising a plurality of stacked laminated core members disposed arounda shaft and at least one integral core-lamination of a differentconfiguration located intermediately within said laminated core members,said laminated core members and said at least one integralcore-lamination having been of the same initially formed configuration,comprising the steps of:(a) forming at least one integralcore-lamination by stamping from a flat rolled magnetic steel sheet apredetermined basic shape having sections to serve as stacked laminatedcore members and including peripheral portions annularly connectingadjacent core lamination sections to form said at least one integralcore-lamination, wherein said peripheral portions may be one or both ofinner and outer peripheral portions; (b) further forming stackedlaminated core members by similarly stamping additional laminations ofsame material and said predetermined basic shape; (c) determiningwhether outer peripheral connecting portions of individual ones of saidadditional laminations are to be cut and, if so, cutting selected onesof said outer peripheral portions; (d) determining whether innerperipheral connecting portions of individual ones of said additionallaminations are to be cut and, if so, cutting selected ones of saidinner peripheral portions; and (e) stacking said cut additionalpredetermined shape core member laminations together with said at leastone basic integral core-lamination to form an integral laminated core;wherein said at least one integral core-lamination and said additionalcore laminations are respectively formed by progressively performingstamping operations by one progressive die machine which can carry outvarious processes while choosing desired press-stations, and said atleast one integral core-lamination and said additional core laminationsare joined with each other by press fitting in a last press station ofsaid progressive die machine, whereby said laminated core memberslocated at desired positions are connected with each other by annularconnecting portions in a relative arrangement of a finished rotorassembly.
 2. A method of manufacturing a rotor for a synchronous motorcomprising a plurality of stacked laminated core members disposed arounda shaft and at least one integral core-lamination of a differentconfiguration located intermediately within said laminated core members,said laminated core members and said at least one integralcore-lamination having been of the same initially formed configuration,comprising the steps of:(a) forming at least one integralcore-lamination by stamping from a flat rolled magnetic steel sheet apredetermined basic shape having sections to serve as stacked laminatedcore members and including peripheral portions annularly connectingadjacent core lamination sections to form said at least one integralcore-lamination, wherein said peripheral portions may be one or both ofinner and outer peripheral portions; (b) further forming stackedlaminated core members by similarly stamping additional laminations ofsame material and said predetermined basic shape; (c) determiningwhether outer peripheral connecting portions of individual ones of saidadditional laminations are to be cut and, if so, cutting selected onesof said outer peripheral portions; (d) determining whether innerperipheral connecting portions of individual ones of said additionallaminations are to be cut and, if so, cutting selected ones of saidinner peripheral portions; (e) stacking said cut additionalpredetermined shape core member laminations together with said at leastone basic integral core-lamination to form an integral laminated core;and (f) inserting rod members into rod holes axially penetrating throughgenerally center portions of said stacked core member laminations andsaid at least one integral core-lamination, connecting said rod membersto annular end plates arranged at both axial ends of the laminated coremembers and fixing each end plate to said shaft, wherein said coremember laminations are formed when so assembled to provide a centralopening in said rotor of diameter greater than that of said shaft suchthat a gap is defined between said core member laminations and saidshaft so said core member laminations are supported against externalforce only by said end plates and said rod members; wherein said atleast one integral core-lamination and said additional core laminationsare respectively formed by progressively performing stamping operationsby one progressive die machine which can carry out various processeswhile choosing desired press-stations, and said at least one integralcore-lamination and said additional core laminations are joined witheach other by press fitting in a last press station of said progressivedie machine, whereby said laminated core members located at desiredpositions are connected with each other by annular connecting portionsin a relative arrangement of a finished rotor assembly.